Applying the vehicle brakes while the vehicle is moving at a slow speed can sometimes result in a high intensity, low frequency vibration or noise that is commonly referred to as brake groan or creep groan.
Some skilled artisans believe that brake groan is caused by the ‘stick-slip’ effect, which involves a stick-phase where the brake lining and rotor are momentarily stuck and move together (no slippage at their interface) and a slip-phase when those two components break free of one another (slippage at their interface). Not wanting to be bound by any particular theory, it is believed that the time period of the stick-phase is variable and depends on factors such as speed, brake load, and system stiffness. When the slip-phase begins, the sudden energy burst results in a vibration that can produce an audible oscillation.